docs: def highpass(self, frequency, q=0.707):
          """highpass takes 2 parameters: filter frequency in Hz below which
          frequencies will be attenuated and q (default=0.707).
  
          Beware of clipping when using high q values.
          """
          self.command.append('highpass')
          self.command.append(frequency)
          self.command.append(str(q) + 'q')
          return self